Lab david

lab-david/.eslintignore

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+**/node_modules/*
+**/vendor/*
+**/*.min.js
+**/coverage/*
+**/build/*

lab-david/.eslintrc.json

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+{
+    "env": {
+      "browser": true,
+      "node": true,
+      "commonjs": true,
+      "jest": true,
+      "es6": true
+    },
+    "globals": {
+      "err": true,
+      "req": true,
+      "res": true,
+      "next": true
+    },
+    "extends": "eslint:recommended",
+    "parserOptions": {
+      "sourceType": "module"
+    },
+    "rules": {
+      "no-console": "off",
+      "indent": [ "error", 2 ],
+      "quotes": ["error", "single", { "allowTemplateLiterals": true }],
+      "comma-dangle": ["error", "always-multiline"],
+      "semi": [ "error", "always" ]
+    }
+  }

lab-david/.gitignore

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+
+# Created by https://www.gitignore.io/api/node,macos,visualstudiocode
+
+### macOS ###
+*.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+### Node ###
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Typescript v1 declaration files
+typings/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+
+
+### VisualStudioCode ###
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+.history
+
+# End of https://www.gitignore.io/api/node,macos,visualstudiocodes

lab-david/__test__/fp.test.js

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+'use strict';
+
+const fp = require('../lib/fp.js');
+
+describe('fp.reduce', () => {
+  test('applies a function against an accumulator and each element in the array to reduce it to a single value', () => {
+    expect(fp.reduce(
+      (accumulator, currentValue) => {
+        return accumulator + currentValue;
+      },
+      [3,3,3],
+      0
+    )).toBe(9);
+  });
+
+  test('An exception should be thrown if the callback is not a function', () => {
+    expect(
+      () => {
+        fp.reduce(`I'm totally a function ()`, [3,3,3], 0);
+      }
+    ).toThrow();
+  });
+});
+
+describe('fp.map', () => {
+  test('applies a function against each element in the array and creates a new array', () => {
+    expect(fp.map(
+      (x) => {
+        return x + 1;
+      },
+      [3,3,3]
+    )).toEqual([4,4,4]);
+  });
+
+  test('An exception should be thrown if the callback is not a function', () => {
+    expect(
+      () => {
+        fp.map(`I'm totally a function ()`, [3,3,3], 0);
+      }
+    ).toThrow();
+  });
+});
+
+describe('fp.filter', () => {
+  test('creates a new array with all elements that pass the test by the function', () => {
+    expect(fp.filter(
+      (x) => {
+        return x > 0;
+      },
+      [0, 1, 2]
+    )).toEqual([1, 2]);
+  });
+
+  test('an exception should be thrown if the callback is not a function', () => {
+    expect(
+      () => {
+        fp.filter(`I'm totally a function ()`, [3,3,3], 0);
+      }
+    ).toThrow();
+  });
+});
+
+describe('fp.slice', () => {
+  test('returns a portion of the old array into a new array according to position specified', () => {
+    expect(fp.slice(
+      0,
+      [0,1,2,3]
+    )).toEqual([0]);
+  });
+
+  test('an exception should be thrown if the collection is not an array-like object', () => {
+    expect(
+      () => {
+        fp.slice(1, 2, 3);
+      }
+    ).toThrow();
+  });
+});

lab-david/lib/fp.js

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+'use strict';
+
+const fp = module.exports = {};
+
+fp.reduce = (callback, collection, initialValue) => {
+  if(typeof callback !== 'function')
+    throw new TypeError('<callback> should be a function!');
+  return Array.prototype.reduce.call(collection, callback, initialValue);
+};
+
+fp.map = (callback, collection) => {
+  if(typeof callback !== 'function')
+    throw new TypeError('<callback> should be a function!');
+  return Array.prototype.map.call(collection, callback);
+};
+
+fp.filter = (callback, collection) => {
+  if(typeof callback !== 'function')
+    throw new TypeError('<callback> should be a function!');
+  return Array.prototype.filter.call(collection, callback);
+};
+
+fp.slice = (begin, end, collection) => {
+  if(typeof callback !== 'object')
+    throw new TypeError('<collection> should be an array like object');
+  return Array.prototype.slice.call(collection, begin, end);
+};